Field of the Invention and Related Art Statement
The present invention relates to a medical system having a means for reducing an emission and permeation of undesirable noises.
In recent years, an endoscope has widely been utilized. The endoscope is capable of observing an organ within a body cavity by intubating an elongate intubation unit into the body cavity. The endoscope is also capable of performing a variety of cure treatments by use of a treatment tool inserted in a treatment tool channel as the necessity arises.
In addition, a variety of electronic endoscopes have hitherto been proposed. In those endoscopes, a tip of the intubation unit is provided with a solid-state imaging element such as a charge coupled device (CCD) as an imaging means. The image information is fetched as a photoelectrically-converted electric signal.
In the case of the electronic endoscope system conceived as a medical system, a circuit unit (patient circuit) intubated into a patient body and a circuit unit (secondary circuit) connected to peripheral units such as a monitor or the like are, as disclosed in, e.g., U.S. Pat. No.4,931,867, isolated by an isolation means to ensure safety.
Namely, if no isolation is effected by the isolation means, and when the isolation from the ground (abbreviated as GND) is declined or deteriorated due to an accident, an electric current is expected to flow down to GND via a human body into which the endoscope intubated. Presumably, this creates a highly dangerous situation. In contrast, however, the patient circuit is isolated from the secondary circuit by the isolation means. In this case, even if the decline of isolation happens, the current flows to GND on the side of only one circuit, thereby ensuring the safety. For instance, when running in the patient circuit alone, the current is low, and hence the patient is only slightly influenced. When running in only the secondary circuit, the patient is protected because of the patient circuit being insulated.
GNDs of the patient circuit and the secondary circuit are not, however, made common by the isolation means. This in turn makes easy a radiation of signals as electric waves outside the system via a floating capacity or the like. Besides, the electric waves from the outside readily intermix (permeate) in an interior of the system via the floating capacity.
For example, the electric signals employed in the electronic endoscope system are radiated to other electric devices. This results in a possibility to produce noises (referred to as radiant noises) which cause a malfunction. Moreover, noises (referred to as radiant noises) radiated from other electronic devices tend to intermix in the electronic endoscope system. For instance, video signals are intermixed with the noises, with the result that a quality of the endoscope image declines. When control signals are intermixed with the noises, this causes a malfunction.
In general, a variety of signals assuming different levels are dealt with inside the electronic endoscope system, For this reason, it is desirable to have a function to restrain the unnecessary radiation of noises as much as possible and also the permeation of the radiated noises.
In a recent situation, it is increasingly desirable to take sufficient countermeasures against EMC (a generic name of EMI (a problem of causing an electromagnetic interference) and EMS (a problem of undergoing the electromagnetic interference)) typically with respect to the electric equipment.